Capacitive electronic pen

ABSTRACT

A capacitive electronic pen includes a housing, a core body, and a peripheral electrode. In the capacitive electronic pen, the core body includes an electrode core formed of a conductor having a spherical section and a shaft center section. The spherical section of the electrode core is not surrounded by the peripheral electrode and is disposed on a tip (distal) end of the capacitive electronic pen protruding from one opening in the axial direction of the housing. The shaft center section of the electrode core has multiple portions that vary in thickness (a cross-section size) including a thin portion, which coupled with the spherical section, and a thick portion. When the core body is fitted to the core body holder, at least a portion of the shaft center section of the electrode core is thinner than the diameter of the spherical section of the electrode core.

BACKGROUND Technical Field

The present invention relates to a capacitive electronic pen.

Description of the Related Art

A capacitive electronic pen uses capacitive coupling to exchange signalswith a position sensor of a position detection device. The positiondetection device detects a position designated by a pen tip of theelectronic pen, by detecting a position on the position sensor that isexchanging signals with the electronic pen through an electric field.

The pen tip of the capacitive electronic pen needs to be electricallyconductive in order to achieve capacitive coupling to the positionsensor. Therefore, the capacitive electronic pen is configured such thatthe distal end of a core body (an elongated core member) formed of aconductive material protrudes from an opening of the housing of theelectronic pen while an end opposite the distal end of the core body isfitted to a core body holder disposed in the housing and engaged(secured) in the housing of the electronic pen (refer, for example, toWO 2016/063420A1).

In many cases, the core body is mainly formed of a rod-shaped metalhaving a predetermined thickness (e.g., a predetermined diameter). Acertain proposed core body is formed of rod-shaped elastomer or otherresin that is made conductive by being mixed with conductive metalpowder. The core body formed by using elastomer as the resin isadvantageous in that the writing performance (the writing feel) of theelectronic pen thus formed can be made to suit writing operationperformed to designate a position on an input surface (writing surface)of the position sensor.

The position detection device is preferably suited for variousapplications and capabilities, such as the capability to detect aninclination angle of the electronic pen with respect to the inputsurface during writing and using the detected inclination angle forcontrolling the thickness (stroke width) of handwriting.

Various methods are proposed for detecting an inclination angle of theelectronic pen with respect to the input surface. Also known is a methodof detecting an inclination angle based on the capacitive couplingbetween the core body and the position sensor. For example, referring toFIG. 8A, in a case where a rod-shaped core body 100 having apredetermined thickness is used as the core body of the electronic pen,in a state where the core body 100 is perpendicular to the input surfaceof the position sensor as indicated by a solid line in FIG. 8A, thetrace of the designated position based on the capacitive coupling withthe core body 100 of the electronic pen is detected as a perfect circle102 by the position sensor as indicated in FIG. 8B.

Meanwhile, in a state where the core body 100 is inclined with respectto the input surface of the position sensor as indicated by a brokenline in FIG. 8A, the trace of the designated position based on thecapacitive coupling with the core body 100 of the electronic pen isdetected by the position sensor as an oval 103 that is elongatedaccording to the direction and angle of inclination of the core body100, as indicated in FIG. 8C. Therefore, the position detection deviceis capable of detecting the direction and angle of inclination of theelectronic pen from the elongated shape (ellipse) of the oval 103.

As is obvious from the above description, in order to detect theinclination angle of the electronic pen with respect to the inputsurface using the method of detecting the inclination based on thecapacitive coupling between the core body and the position sensor, itmay be necessary that not only the distal end of the core body but alsoa portion adjacent to the distal end be capacitively coupled to theposition sensor. Further, it may be preferable that not only the distalend of the core body but also a trailing (proximal) end portion thatcontinues from the distal end be thick, i.e., have a large cross-section(e.g., a large diameter).

BRIEF SUMMARY

As described above, the core body formed of elastomer or other resinmade conductive is advantageous in that it makes it easy to adjust thefeel of writing. However, resin, such as elastomer, is easily deformed.Therefore, when high pen pressure is applied to the pen tip of theelectronic pen, the pen tip end of the core body might deform to becaught (stuck) in the opening of the housing of the electronic pen todegrade the writing performance or writing experience for the user.

Therefore, the core body formed of elastomer or other resin, which ismade conductive, needs to be thick enough so as not to be deformedeasily. Additionally, the circumference of a portion of the core bodyopposing the opening of the housing needs to be reinforced with harderresin. On the other hand it is generally preferred that the electronicpen be thinned and, accordingly, it is preferable that the core body bethinned as well. The competing considerations, however, make itdifficult to thin the core body, to present an obstacle to the thinningof the electronic pen. Further, there is an additional problem that thecore body formed of elastomer or other resin made conductive cannot beeasily thinned in order to assure conductivity which requires a certaindegree of thickness.

Meanwhile, using the core body formed of metal is advantageous in thatconductivity is easily maintained even when the core body is thin, andthat adequate strength is provided when a pen pressure is applied to thepen tip end of the core body. However, as described above, the core bodystill needs to be thick in a case where the inclination angle of theelectronic pen is to be detected.

Stated differently, for the purpose of detecting the inclination angleof the electronic pen, not only the distal end of the core body but alsothe trailing end portion adjacent to the distal end needs to have acertain degree of thickness so as to support capacitive coupling withthe position sensor no matter whether the core body is formed ofelastomer or other resin made conductive or formed of metal.

However, in a case where the thickness of the core body is configured asdescribed above, there arises a problem where the position designated bythe electronic pen is affected by the capacitive coupling between theposition sensor and the trailing end portion of the core body thatcontinues from the distal end. Therefore, when a straight line is drawnwhile the electronic pen is inclined obliquely with respect to the inputsurface, the trace detected by the position detection device may becomewavy (because of a waving phenomenon) and not linear.

In view of the above circumstances, according to various exemplaryembodiments, an electronic pen is provided that makes it possible tothin the core body in response to a demand for thinner electronic pens,that can detect the inclination angle of the electronic pen, and thatavoids the waving phenomenon.

According to various exemplary embodiments, a capacitive electronic penis provided that includes a housing, a core body, and a peripheralelectrode. The housing is cylindrical in shape. The core body isconfigured such that a distal end thereof protrudes from one opening inthe axial direction of the housing, and that a trailing end opposing thedistal end in the axial direction is detachably fitted to a core bodyholder disposed in the hollow space of the housing. The peripheralelectrode is positioned near the one opening of the housing and formedof a conductor disposed so as to surround at least a portion of the corebody excluding the distal end. The core body includes an electrode coreformed of a conductor having a spherical section and a shaft centersection. The shaft center section is coupled to the spherical section.The spherical section of the electrode core is not surrounded by theperipheral electrode and is disposed on the distal end protruding fromthe one opening in the axial direction of the housing. The shaft centersection of the electrode core has portions that vary in thickness alongthe axial direction. Those portions includes a coupling portion thatcouples to the spherical section and is thinner than the diameter of thespherical section, and a portion that is disposed toward the trailingend of the core body and is thicker than the coupling portion. When thecore body is fitted to the core body holder, at least a portion of theshaft center section of the electrode core that is not surrounded by theperipheral electrode is thinner than the diameter of the sphericalsection of the electrode core.

The electronic pen having the above-described configuration may beconfigured to detect the inclination angle of the electronic pen, byusing the capacitive coupling between the peripheral electrode and theposition sensor, instead of using the capacitive coupling between thecore body and the position sensor to detect the inclination of theelectronic pen. Therefore, the portion continuing from the distal end ofthe core body need not be made thick in order to detect the inclinationof the electronic pen.

In the electronic pen having the above-described configuration, the corebody includes the electrode core formed of a conductor having thespherical section and the shaft center section. Further, the electronicpen having the above-described configuration includes the distal endprotruding from the one opening of the housing of the electronic pen,and the spherical section of the electrode core formed of a conductor isdisposed on the distal end. As the electrode core has a spherical distalend having a spherical shape, the capacitive coupling with the positionsensor is uniform irrespective of the inclination of the electronic penand, as a result, the position detection device is capable of accuratelydetecting a designated position.

Further, the coupling portion of the shaft center section that couplesto the spherical section is thinner than the diameter of the sphericalsection. Still further, when the core body is fitted to the core bodyholder in the housing of the electronic pen, at least a portion of theshaft center section of the electrode core that is not surrounded by theperipheral electrode is thinner than the diameter of the sphericalsection of the electrode core. Therefore, even when the electronic penis inclined, the above-described configuration reduces the capacitivecoupling between the position sensor and at least the portion of theshaft center section of the electrode core that is not surrounded by theperipheral electrode. Consequently, when a straight line is drawn evenwhen the electronic pen is inclined with respect to the input surface,it is possible to reduce the waving phenomenon and thus prevent thestraight line from becoming wavy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams illustrating an example configuration of anelectronic pen according to an embodiment of the present invention;

FIGS. 2A and 2B are diagrams illustrating an example configuration of acore body used in the electronic pen according to the embodiment of thepresent invention;

FIG. 3 is a diagram illustrating a configuration of certain parts of theelectronic pen according to the embodiment of the present invention;

FIG. 4 is a diagram illustrating an example configuration of anelectronic circuit of the electronic pen according to the embodiment ofthe present invention;

FIGS. 5A and 5B are diagrams illustrating an example of operationperformed by the electronic circuit depicted in FIG. 4;

FIGS. 6A to 6F are diagrams illustrating an inclination detectionoperation performed by the electronic pen according to the embodiment ofthe present invention;

FIGS. 7A and 7B are diagrams illustrating alternative exampleconfigurations of the core body used in the electronic pen according toan embodiment of the present invention; and

FIGS. 8A to 8C are diagrams illustrating an inclination detectionoperation performed by a conventional electronic pen.

DETAILED DESCRIPTION

FIGS. 1A and 1B are diagrams illustrating an example configuration of acapacitive electronic pen according to an embodiment of the presentinvention. FIG. 1A is a diagram illustrating the appearance of acapacitive electronic pen 1 according to the embodiment. FIG. 1B is alongitudinal cross-sectional view illustrating a configuration ofcertain parts of the capacitive electronic pen 1 according to theembodiment.

As depicted in FIGS. 1A and 1B, a housing 10 of the electronic pen 1according to the embodiment is configured such that a front cap 12,which is a conically-shaped cylindrical body, is fitted and mounted intoan opening in a pen tip end of a cylindrical housing main body section11. The housing main body section 11 is formed of a conductive material,such as metal, such that the housing main body section 11 is grounded(earth grounded) through a human body when a user holds and operates theelectronic pen 1. Further, the front cap 12 is formed of an insulatingmaterial, such as resin.

As depicted in FIG. 1B, an opening 12 a is formed in the pen tip end,which is a tapered portion of the front cap 12. The opening 12 a permitsthe insertion of a core body 20 such that it can freely move in theaxial direction. As described later, the core body 20 is configured tobe conductive. The core body 20 is inserted into the housing of theelectronic pen 1 through the opening 12 a in the front cap 12 such thata distal end 20 a of the core body 20 is protruded outward and retainedby a later-described core body holder 30. In this instance, the corebody 20, which is conductive, and the housing main body section 11,which is formed of a conductive material, are electrically separated(insulated) from each other because the front cap 12 is disposed betweenthem.

As depicted in FIGS. 1A and 1B, a circuit board holder 40 and a battery42 are accommodated in the hollow space of the housing main body section11. The circuit board holder 40 is configured such that a printedcircuit board 41 is mounted on a circuit board mounting base 401. Thebattery 42, which acts as a power supply, may be a primary battery or asecondary battery (rechargeable battery). A trailing end of the housingmain body section 11, which is positioned opposite the pen tip end ofthe housing main body section 11, is blocked by a back cap 13 asdepicted in FIG. 1A.

The circuit board holder 40, which is formed of insulating resin,includes a pressure-sensitive part retaining section 402. Thepressure-sensitive part retaining section 402 is disposed in alongitudinal direction, which is the axial direction of the electronicpen 1, and positioned opposite the circuit board mounting base 401. Asdepicted in FIG. 1B, the circuit board holder 40 is configured such thatthe pressure-sensitive part retaining section 402 and the circuit boardmounting base 401 are disposed in the longitudinal direction, which isthe axial direction of the electronic pen 1, and positioned contiguous(adjacent) to each other when the circuit board holder 40 isaccommodated in the hollow space of the housing main body section 11.The pressure-sensitive part retaining section 402, which iscylindrically shaped, has a hollow space for accommodatingpressure-sensitive parts 50 (a plurality of pen pressure detectionparts). The circuit board mounting base 401 is shaped like a board onwhich the printed circuit 41 is mounted and retained. The shape of thecircuit board mounting base 401 results from cutting a cylindrical bodyapproximately into half.

The pressure-sensitive parts 50 and a pressure transmission member,which are included in a pen pressure detection section, are accommodatedin the pressure-sensitive part retaining section 402 of the circuitboard holder 40. The pen pressure detection section in the presentexample includes a variable capacitor, whose capacitance varies inaccordance with a pen pressure applied to the core body 20.

As depicted in FIG. 1B, the pressure-sensitive parts 50 in the presentexample are a plurality of parts including a dielectric 51, a terminalmember 52, a retaining member 53, a conductive member 54, and an elasticmember 55. The terminal member 52 is formed of a conductive material,such as steel special use stainless (SUS), disposed on one end face ofthe dielectric 51, which is shaped like a disk, and configured as afirst electrode of the variable capacitor formed of thepressure-sensitive parts 50.

The conductive member 54 is formed, for example, of conductive rubber,shaped like a column, and is retained by the retaining member 53. Theend face of the conductive member 54 is disposed to oppose the other endface of the dielectric 51. The surface of the conductive member 54 thatopposes the dielectric 51 is shaped like a dome, for example.

The elastic member 55 includes a coil spring that is formed of aconductive material such as SUS, and is disposed in such a manner thatthe conductive member 54 is inserted into the space of the coil spring.The conductive member 54 and the elastic member 55 are electricallyconnected and configured as a second electrode of the variablecapacitor. The elastic member 55 is disposed between the dielectric 51and the retaining member 53, and configured to constantly press theconductive member 54 in the direction of separating it from thedielectric 51.

A cylindrical section 32 is disposed toward the opening in the pen tipend of the cylindrical pressure-sensitive part retaining section 402 ofthe circuit board holder 40. The cylindrical section 32 not only engages(secures) the pressure-sensitive parts 50 in the pressure-sensitive partretaining section 402, but also accommodates the core body holder 30.

The core body holder 30 is formed of a conductive material, such as SUS,and is integrally shaped by combining an accommodation fitting section301 and a rod-shaped section 302. The accommodation fitting section 301has a hole in which a conductive elastic member 31 is accommodated andfitted. The rod-shaped section 302 fits into the retaining member 53included in the pressure-sensitive parts 50.

The core body 20 is coupled to and retained by the core body holder 30when an (proximal) end opposite from the distal end 20 a of the corebody 20 is fitted to the core body holder 30, which is formed of aconductive material, through the conductive elastic member 31. Therod-shaped section 302 of the core body holder 30, which opposes thecore body 20, is fitted to the retaining member 53 included in thepressure-sensitive parts 50 such that the core body 20 and the core bodyholder 30 are integrally displaced in the axial direction according tothe pressure applied to the distal end 20 a of the core body 20. As aresult, the pressure (pen pressure) applied to the distal end 20 a ofthe core body 20 is transmitted to the pressure-sensitive parts 50.

Consequently, in the present example, the core body holder 30 having theconductive elastic member 31 is configured to function as a pressuretransmission member for transmitting the pressure (pen pressure) that isapplied to the core body 20 to the pressure-sensitive parts 50.

As depicted in FIG. 1B, a coil spring 33 is disposed in the cylindricalsection 32 so as to constantly press the core body holder 30 toward thecore body 20. The coil spring 33 is formed of a conductive material,such as conductive metal. Although not depicted in FIGS. 1A and 1B, thecoil spring 33 is electrically connected at a first end to the outputend of a signal transmission circuit disposed on the printed circuitboard 41.

As the core body holder 30 is formed of a conductive material, the corebody 20, which is formed of a conductive material and attached to thecore body holder 30 via the conductive elastic member 31, iselectrically connected via the coil spring 33 to the signal transmissioncircuit disposed on the printed circuit board 41.

In the electronic pen 1 in the present example, when the pressure (penpressure) is applied toward the distal end 20 a of the core body 20, thecore body 20 is displaced in the axial direction toward the inside ofthe housing main body section 11 of the electronic pen 1. Then, the corebody holder 30, to which the core body 20 is fitted, is displaced in theaxial direction jointly with the core body 20. This displaces theconductive member 54 toward the dielectric 51 against the elastic forceof the elastic member 55 included in the pressure-sensitive parts 50.Then, a contact area between the conductive member 54 and the dielectric51 varies in accordance with the applied pressure, such that thecapacitance of the variable capacitor, which is included in the penpressure detection section, varies in accordance with the appliedpressure. Consequently, the pen pressure can be detected from thecapacitance of the variable capacitor included in the pen pressuredetection section.

As depicted in FIG. 1B, the electronic pen 1 in the present example isconfigured such that a peripheral electrode 60 formed of a conductivematerial is disposed in the front cap 12 in such a manner as to surrounda portion of the core body 20 excluding the distal end 20 a. In thepresent example, the peripheral electrode 60 is formed by coiling aconductive metal wire. In the present example, a cylindrically-shapedperipheral electrode retaining section 61 formed of insulating resin isfitted to the pen tip end circumference of the pressure-sensitive partretaining section 402 of the circuit board holder 40. The peripheralelectrode retaining section 61 is shaped similarly to the inner wallsurface of the front cap 12 such that a space is formed between theperipheral electrode retaining section 61 and the inner wall surface ofthe front cap 12. As depicted in FIG. 1B, the peripheral electrode 60 isdisposed in the space between the circumferential surface of thecylindrically-shaped peripheral electrode retaining section 61 and theinner wall surface of the front cap 12. Although not depicted in FIG.1B, a coil member included in the peripheral electrode 60 iselectrically connected to circuit components on the printed circuitboard 41.

A cylindrical section 121 is formed in the hollow space of the front cap12, which is positioned inward from the opening 12 a, and is shapedalong the axial direction. The peripheral electrode 60 is electricallyseparated (insulated) from the conductive core body 20 by the peripheralelectrode retaining section 61 and the cylindrical section 121.

A configuration of the core body 20 will now be described. FIG. 2A is aside view illustrating the appearance of the core body 20. FIG. 2B is alongitudinal cross-sectional view illustrating the core body 20.

As depicted in FIG. 2A, the appearance of the core body 20 in thepresent example is such that the distal end 20 a, which isconically-shaped, is formed on a first axial end of a rod-shaped corebody main body section 20 b having a circular cross section. In thepresent example, the diameter D1 of the bottom surface of the cone ofthe conically-shaped distal end 20 a is larger than the diameter of thecore body main body section 20 b such that a shoulder section 20 c isformed between the distal end 20 a and the core body main body section20 b.

In the present embodiment, a portion of the core body main body section20 b that is positioned toward the coupling portion that couples to thedistal end 20 a is shaped like a column having a diameter D2 smallerthan the diameter D1 of the bottom surface of the cone of the distal end20 a. Further, a portion of the core body main body section 20 b thatengages with the retaining member 53 of the pressure-sensitive parts 50is shaped like a column having a diameter D3 smaller than the diameterD2, so as to correspond to the size of a fitting hole of the retainingmember 53. In the present example, therefore, the core body main bodysection 20 b, which includes a column-shaped section having the diameterD2 and a column-shaped section having the diameter D3, is configuredsuch that a shoulder section 20 d is formed between these twocolumn-shaped sections.

As depicted in FIGS. 2B and 1B, the core body 20 in the presentembodiment includes an electrode core 21 formed of metal as an exampleof a conductive member, and is configured such that the pen tip end inthe axial direction of the electrode core 21 is covered with insulatingresin 22. In the present example, hard resin is used as the resin 22 andformed, for example, of polyoxymethylene (POM).

As depicted in FIGS. 2B and 1B, the electrode core 21 includes aspherical section 211 and a shaft center section 212. In the presentexample, the electrode core 21 is configured as an integral metalobject. It is obvious that the spherical section 211 and the shaftcenter section 212 may be regarded (or configured) as separate membersand combined together.

The spherical section 211 of the electrode core 21 is configured to bepositioned within the distal end 20 a of the core body 20. That is, thespherical section 211 is covered with the resin 22 to form theconically-shaped distal end 20 a. In the present embodiment, the distalend 20 a is formed of the resin 22 such that a section 22 a of thedistal end 20 a that is positioned toward the side coupling with thecore body main body section 20 b and has a predetermined length in theaxial direction is shaped like a column having the diameter D1. Stateddifferently, the column-shaped section 22 a that has the predeterminedlength and is positioned toward the side coupling with the core bodymain body section 20 b has a side circumferential surface along theaxial direction.

In the present example, the shaft center section 212 of the electrodecore 21 includes three portions 212 a, 212 b, and 212 c that aredisposed in the axial direction and different in thickness.

As depicted in FIGS. 2B and 1B, the portion 212 a includes a couplingportion that couples with the spherical section 211, has a diametersmaller than the diameter Do of the spherical section 211, and iscovered with the resin 22. The portion 212 a is hereinafter referred toas the electrode core thin shaft center portion. As depicted in FIGS. 2Band 1B, the electrode core thin shaft center portion 212 a in thepresent example is tapered in shape, i.e., thinnest at the couplingportion that couples with the spherical section 211 and graduallyincreased in diameter with an increase in the distance (i.e., fartheraway) from the spherical section 211. As depicted in FIG. 2B, themaximum diameter of the electrode core thin shaft center portion 212 ain the present example is diameter Ds, which is smaller than thediameter Do of the spherical section.

The vicinity of the coupling portion of the electrode core thin shaftcenter portion 212 a which coupled to the spherical section 211 iswithin the distal end 20 a of the core body 20 and covered with theresin 22 of the distal end 20 a. The remaining portion of the electrodecore thin shaft center portion 212 a is covered with the resin 22 toform a column-shaped section 22 b having the diameter D2. In this case,the remaining portion of the electrode core thin shaft center portion212 a is positioned in the vicinity of the center of the column-shapedsection 22 b having the diameter D2. The circumferential side surface ofthe column-shaped section 22 b having the diameter D2 is formed alongthe axial direction.

As shown in FIGS. 2A and 2B, the portion 212 b is equal in diameter tothe column-shaped section 22 b having the diameter D2, which is coveredwith the resin 22, and is exposed without being covered with the resin22. The portion 212 b is hereinafter referred to as the electrode corethick shaft center portion. As depicted in FIGS. 2A and 2B or FIG. 1B,the circumferential side surface of the electrode core thick shaftcenter portion 212 b is flush with the circumferential side surface ofthe column-shaped section 22 b having the diameter D2, which is coveredwith the resin 22.

As further shown in FIGS. 2A and 2B, the portion 212 c, which is exposedwithout being covered with the resin, forms a column-shaped section thathas the diameter D3 and is extended toward the trailing end from theelectrode core thick shaft center portion 212 b. The portion 212 c ishereinafter referred to as the electrode core trailing end portion. Asdepicted in FIG. 1B, the end of the electrode core trailing end portion212 c is fitted to the core body holder 30 via the conductive elasticmember 31.

As described above, the core body holder 30 is electrically connectedvia the conductive coil spring 33 to the output end of the signaltransmission circuit disposed on the printed circuit board 41.Therefore, the output end of the signal transmission circuit disposed onthe printed circuit board 41 is electrically connected to the electrodecore trailing end portion 212 c of the core body 20 via the conductivecoil spring 33, the core body holder 30, and the conductive elasticmember 31. That is, an output signal from the signal transmissioncircuit disposed on the printed circuit board 41 is supplied to theelectrode core 21 of the core body 20, and a signal is transmitted to aposition sensor via capacitive coupling with the spherical section 211of the electrode core 21.

It should be noted that, as depicted in FIG. 1B, the core body 20 caneasily be inserted and fitted into the conductive elastic member 31accommodated in the core body holder 30, and can easily be pulled out ofthe core body holder 30 when pulled with a predetermined force.

Referring now to FIG. 3, the following describes the positional relationbetween the core body 20 and the peripheral electrode 60 and, forexample, the relation between the housing 10 and the opening 12 a in thefront cap 12 of the pen tip end, in a case when the core body 20 isinserted into the housing 10 from the opening 12 a in the front cap 12of the electronic pen 1 and is fitted to the core body holder 30. FIG. 3is an enlarged longitudinal cross-sectional view illustrating the pentip end of the capacitive electronic pen 1 according to the presentembodiment.

As depicted in FIG. 3 and FIG. 1B, in a state where the core body 20 isfitted to the core body holder 30, the electrode core thick shaft centerportion 212 b and the electrode core trailing end portion 212 c, whichare configured such that the electrode core 21 of the core body 20 isexposed to the outside, are positioned within the space covered by theperipheral electrode 60. Further, in the present example, in the section22 b where the electrode core thin shaft center portion 212 a is coveredwith the resin 22 to have the diameter D2, a defined length portion ofthe electrode core thin shaft center portion 212 a on the side thatcouples with the electrode core thick shaft center portion 212 b ispositioned within the space covered by the peripheral electrode 60. Aportion of the electrode core that is covered by the peripheralelectrode 60 is electrostatically shielded by the peripheral electrode60 and thus is not readily capacitively coupled to the position sensor.Consequently, signals transmitted from this portion of the electrodecore 21 of the core body 20 is substantially negligible.

Moreover, although a portion of the core body 20 that is positionedtoward the distal end 20 a of the electrode core thin shaft centerportion 212 a is outside the space covered by the peripheral electrode60, the portion toward the distal end 20 a of the electrode core thinshaft center portion 212 a has a diameter smaller than the diameter Doof the spherical section 211. Therefore, the portion toward the distalend 20 a of the electrode core thin shaft center portion 212 a, which isoutside the space covered by the peripheral electrode 60, is coupledless strongly as compared to capacitive coupling between the sphericalsection 211 and the position sensor. Consequently, signals transmittedfrom this portion of the electrode core 21 of the core body 20 issubstantially negligible.

As the electrode core thin shaft center portion 212 a is tapered inshape in the present embodiment, the maximum diameter Ds' of the portionof the electrode core thin shaft center portion 212 a that is outsidethe space covered by the peripheral electrode 60 is smaller than themaximum diameter Ds of the electrode core thin shaft center portion 212a. This weakens the capacitive coupling between the tapering portion ofthe electrode core thin shaft center portion 212 a and the positionsensor.

As a result, in the electronic pen 1 according to the presentembodiment, only the signal transmission from the spherical section 211at the distal end of the electrode core 21 of the core body 20 becomesdominant with respect to (as sensed from) the position sensor. Thismakes it possible to reduce a waving phenomenon that is described at thebeginning of the present disclosure. Further, as the spherical section211 is disposed at the distal end of the electrode core 21, it ispossible to achieve capacitive coupling with the position sensor withoutregard to an inclination angle of the electronic pen 1 with respect toan input surface of the position sensor. Consequently, the electronicpen according to the present embodiment has a distinctive technicaladvantage of being able to not only detect the inclination angle of theelectronic pen by using the peripheral electrode 60 as described indetail later, but also to avoid the waving phenomenon in which a lineartrace inputted by the distal end 20 a of the core body 20 becomes wavy.

Furthermore, in the electronic pen 1 according to the presentembodiment, protection against a force obliquely applied to the thinnedcore body 20 is afforded not only by configuring the core body 20 asdescribed above, but also by improving the configuration of the vicinityof the opening 12 a of the front cap 12, which is a part of the housing10 of the electronic pen 1.

Stated differently, the opening 12 a of the front cap 12 iscylindrically formed as depicted in FIG. 3 to form an inner wall surface12 b along the axial direction. In this case, the diameter of theopening 12 a is slightly larger than the diameter D1 (see FIG. 2A) ofthe column-shaped section 22 a of the conically-shaped distal end 20 aof the core body 20 that is positioned toward the coupling portion thatcouples with the core body main body section 20 b. As depicted in FIG.3, in a state where the core body 20 is attached to the electronic pen1, the circumferential side surface of the column-shaped section 22 a ofthe distal end 20 a, which has the diameter D1, opposes the inner wallsurface 12 b of the opening 12 a through a void. Therefore, when theelectronic pen 1 is inclined with respect to the input surface such thatpressure is obliquely applied to the distal end 20 a of the core body20, the circumferential side surface of the column-shaped section 22 aof the distal end 20 a, which has the diameter D1, abuts against theinner wall surface 12 b of the opening 12 a, and thus prevents the corebody 20 from being significantly distorted.

Moreover, as described above, the cylindrical section 121 is disposed onthe inside of the opening 12 a of the front cap 12. The inside diameterof the cylindrical section 121 is slightly larger than the maximumdiameter D2 of the column-shaped section 22 b of the core body main bodysection 20 b. In a state where the core body 20 is fitted to the corebody holder 30, the column-shaped section 22 b of the core body mainbody section 20 b that is positioned toward the distal end 20 a isinserted into the cylindrical section 121.

Consequently, as depicted in FIG. 3, in the state where the core body 20is attached to the electronic pen 1, the circumferential side surface ofthe column-shaped section 22 b of the core body main body section 20 bof the core body 20, which has the diameter D2, opposes an inner wallsurface 121 a of the cylindrical section 121 through a void. Therefore,when the electronic pen 1 is inclined with respect to the input surfacesuch that pressure is obliquely applied to the distal end 20 a of thecore body 20, the circumferential side surface of the column-shapedsection 22 b of the core body main body section 20 b, which has thediameter D2, abuts against the inner wall surface 121 a of thecylindrical section 121, and thus prevents the core body 20 from beingsignificantly distorted.

In the above case, as depicted in FIG. 3, the inner wall surface 121 aof the cylindrical section 121 in the present example is formed over theelectrode core thick shaft center portion 212 b of the electrode core21, which is flush with the circumferential side surface of thecolumn-shaped section 22 b that is included in the core body main bodysection 20 b and has the diameter D2. Therefore, the core body 20 isprotected not only by the column-shaped section 22 b of the core bodymain body section 20 b, which is formed of the resin 22 and has thediameter D2, but also by the cylindrical section 121 in the couplingportion that couples with the electrode core thick shaft center portion212 b formed of metal.

The above-described example assumes that a part of the electrode corethin shaft center portion 212 a of the electrode core 21 is also coveredby the peripheral electrode 60. In the present example, however, themaximum diameter of the electrode core thin shaft center portion 212 ais smaller than the diameter Do of the spherical section 211. Therefore,the electrode core thin shaft center portion 212 a may be configured tobe entirely positioned outside the space covered by the peripheralelectrode 60.

Further, the above-described example assumes that the diameter of theelectrode core trailing end portion 212 c is smaller than the diameterof the electrode core thick shaft center portion 212 b. However, thediameter of the electrode core trailing end portion 212 c mayalternatively be equal to the diameter of the electrode core thick shaftcenter portion 212 b as long as the thickness of the electrode coretrailing end portion 212 c allows it to be fitted to the core bodyholder 30.

Example Configuration of Signal Processing Circuit of Electronic Pen 1

FIG. 4 is a block diagram illustrating an example configuration of asignal processing circuit of the electronic pen 1 according to thepresent embodiment. Specifically, as depicted in FIG. 4, the signalprocessing circuit of the electronic pen 1 according to the presentembodiment includes a controller 501, a signal transmission circuit 502,an open/close switch circuit 503, and a selector switch circuit 504. Aterminal Pc of the controller 501 is grounded through a parallel circuithaving a variable capacitor 50C and a resistor R, which are included inthe pen pressure detection section.

The controller 501 includes, for example, a microprocessor, and isconfigured as a control circuit for controlling the processingoperations of the electronic pen 1. Although not depicted in FIG. 4, apower supply voltage is supplied from the battery 42, which is anexample of a drive power supply. The controller 501 functions as asignal supply control circuit, or more specifically, controls the signaltransmission circuit 502, and provides switching control for theopen/close switch circuit 503 and the selector switch circuit 504.

Further, the controller 501 detects the pen pressure applied to thedistal end 20 a of the core body 20 of the electronic pen 1 bymonitoring capacitance changes in the variable capacitor 50C that occurin accordance to the pen pressure applied to the distal end 20 a of thecore body 20. In the present embodiment, the controller 501 detects thepen pressure based on the discharge time of the variable capacitor 50Cwhose capacitance value is based on the pen pressure applied to thedistal end 20 a of the core body 20.

More specifically, when detecting the pen pressure applied to the distalend 20 a of the core body 20, the controller 501 first charges thevariable capacitor 50C by setting the terminal Pc at a high level. Theterminal Pc is connected to a first end of the variable capacitor 50C.Next, the controller 501 switches the terminal Pc into an input statefor monitoring the voltage at the terminal Pc. In this instance, anelectric charge stored in the variable capacitor 50C is discharged witha discharge time constant that is determined by the resistor Rparallelly connected to the variable capacitor 50C. Then, the voltageacross the variable capacitor 50C gradually decreases. The controller501 determines the time Tp required for the voltage across the variablecapacitor 50C to decrease to a predetermined threshold voltage or lower.The time Tp is equivalent to the pen pressure to be determined. Thecontroller 501 determines a multi-bit pen pressure value from the timeTp.

The signal transmission circuit 502 in the present embodiment includesan oscillator circuit that generates an alternative current signalhaving a predetermined frequency f1, for example, frequency f1 of 1.8MHz. The controller 501 provides on/off control of the oscillatorcircuit by supplying a control signal CT to the oscillator circuitincluded in the signal transmission circuit 502. Therefore, inaccordance with the control signal CT from the controller 501, theoscillator circuit included in the signal transmission circuit 502 turnsthe generated alternative current signal on and off. This causes thesignal transmission circuit 502 to generate a signal Sc including anamplitude-shift keying (ASK) modulated signal. That is, when thecontroller 501 controls the oscillator circuit included in the signaltransmission circuit 502, the signal transmission circuit 502 generatesthe ASK modulated signal. Instead of the ASK modulated signal, thesignal transmission circuit 502 may generate an on-off keying (OOK)modulated signal, a frequency-shift keying (FSK) modulated signal, oranother modulated signal.

The signal Sc from the signal transmission circuit 502 is amplified byan unillustrated amplifier, then, in the present embodiment, supplied tothe electrode core 21 of the core body 20 through the open/close switchcircuit 503, and supplied also to one fixed terminal s of the selectorswitch circuit 504. The other fixed terminal g of the selector switchcircuit 504 is grounded. A movable terminal of the selector switchcircuit 504 is connected to the peripheral electrode 60.

Further, a selector control signal SW supplied from the controller 501provides on/off control of the open/close switch circuit 503, andswitches the selector switch circuit 504 between the fixed terminal sand the fixed terminal g.

In the electronic pen 1 according to the present embodiment, the signalprocessing circuit is configured such that the controller 501 exercisescontrol to execute a position detection period Ta and an inclinationdetection period Tb alternately in a time-division manner as depicted inFIG. 5A. Switching control between the position detection period Ta andthe inclination detection period Tb is provided when the selectorcontrol signal SW from the controller 501 exercises switching control ofthe open/close switch circuit 503 and the selector switch circuit 504 asdepicted in FIG. 5B.

In the position detection period Ta, the signal processing circuitoperates in such a manner that the selector control signal SW from thecontroller 501 turns on the open/close switch circuit 503 so as toconnect the output end of the signal transmission circuit 502 to theelectrode core 21 of the core body 20, and switches the selector switchcircuit 504 to the fixed terminal g in order to ground the peripheralelectrode 60.

Further, in the position detection period Ta, the signal transmissioncircuit 502 generates a position detection signal and pen pressureinformation in accordance with the control signal CT from the controller501, and the generated position detection signal and pen pressureinformation are transmitted from the electrode core 21 of the core body20. The position detection signal is a continuous-wave signal (burstsignal) having the frequency f1. Meanwhile, the pen pressure informationis an ASK signal that is obtained when the signal having the frequencyf1 is modulated by information regarding the multi-bit pen pressurevalue, which is detected and acquired by the controller 501 in themanner described above. Further, in the position detection period Tadescribed in conjunction with the present example, the electrode core 21of the core body 20 first transmits the position detection signal, andthen transmits the pen pressure information.

In the position detection period Ta, the peripheral electrode 60 isgrounded. Therefore, a portion of the electrode core 21 of the core body20 that exists in the space covered by the peripheral electrode 60 iselectrostatically shielded, to avoid being capacitively coupled to theposition sensor. A portion of the electrode core 21 of the core body 20that exists outside the space covered by the peripheral electrode 60 isnot electrostatically shielded. However, this portion includes thespherical section 211 and the electrode core thin shaft center portion212 a of the electrode core 21, and only the spherical section 211 issubstantially coupled capacitively with the position sensor. As aresult, the position detection device is capable of accurately detectinga position designated by the electronic pen 1, while significantlyweakening any capacitive coupling with a portion other than thespherical section 211, to thereby reduce the waving phenomenon.

Next, in the inclination detection period Tb, the selector controlsignal SW from the controller 501 turns off the open/close switchcircuit 503 so as to disconnect the output end of the signaltransmission circuit 502 from the electrode core 21 of the core body 20,and switches the selector switch circuit 504 to the fixed terminal s inorder to connect the output end of the signal transmission circuit 502to the peripheral electrode 60.

Further, in the inclination detection period Tb, the signal transmissioncircuit 502 generates an inclination detection signal in accordance withthe control signal CT from the controller 501. The generated inclinationdetection signal is a continuous-wave signal (burst signal) having thefrequency f1, which is similar to the position detection signal. Itshould be noted that, in the inclination detection period Tb, too, thepen pressure information (ASK signal) may be generated subsequently tothe inclination detection signal.

Consequently, in the inclination detection period Tb, the inclinationdetection signal is transmitted to the position sensor through theperipheral electrode 60. The position detection device detects theinclination angle of the electronic pen 1 based on a detection signalacquired through the position sensor.

Referring now to FIGS. 6A to 6F, the following describes a method thatis used by the position detection device to detect the inclination angleof the electronic pen 1.

When the core body 20 of the electronic pen 1 is perpendicular to theinput surface of a position sensor 201 as depicted in a schematicdiagram of FIG. 6A, capacitive coupling occurs between the positionsensor 201 and the electrode core 21 of the core body 20 in the positiondetection period Ta, and a region OBa where the capacitive couplingoccurs is a perfectly circular region as depicted in FIG. 6B. Meanwhile,in the inclination detection period Tb, capacitive coupling occursbetween the position sensor 201 and the peripheral electrode 60, and aregion OBb where the capacitive coupling occurs is a ring-shaped regionas depicted in FIG. 6C.

Further, when the core body 20 of the electronic pen 1 is inclined withrespect to the input surface of the position sensor 201 as depicted in aschematic diagram of FIG. 6D, the region OBa where capacitive couplingoccurs between the position sensor 201 and the electrode core 21 of thecore body 20 in the position detection period Ta substantially remains aperfectly circular region as depicted in FIG. 6E. Meanwhile, the regionOBb where the capacitive coupling occurs between the position sensor 201and the peripheral electrode 60 in the inclination detection period Tbis an elliptical region that is based on the inclination angle andelongated in the direction of inclination as depicted in FIG. 6F.

Consequently, the position detection device is able to detect themagnitude of the inclination angle of the electronic pen 1 from thelongitudinal length of the elliptical region OBb depicted in FIG. 6F.Further, the position detection device is able to detect the directionof inclination of the electronic pen 1 by detecting the longitudinaldirection of the elliptical region OBb starting from a positiondesignated by the electronic pen 1, which is depicted in FIG. 6E.

It should be noted that, in the example of FIG. 4, the signal having thefrequency f1, which is supplied to the electrode core 21 of the corebody 20, is used for the peripheral electrode 60 configured to detectthe inclination angle. Alternatively, however, the signal supplied tothe electrode core 21 of the core body 20 may differ in frequency fromthe signal supplied to the peripheral electrode 60. When such analternative is used, the position detection device is able todistinguish between the signal from the electrode core 21 and the signalfrom the peripheral electrode 60. Therefore, the signal from theelectrode core 21 and the signal from the peripheral electrode 60 may besimultaneously transmitted to the position sensor instead of repeatingthe position detection period and the inclination detection period inthe time-division manner as described above.

Example Alternative Configurations of Core Body and Electrode Core

The electrode core 21 of the core body 20 according to the previousembodiment is configured such that the electrode core thin shaft centerportion 212 a is tapered in shape. However, the electrode core thinshaft center portion 212 a is not limited to a tapered shape. FIG. 7Adepicts a core body 20A having such an example alternativeconfiguration. Elements identical to those of the core body 20 accordingto the previous embodiment are designated by the same reference numeralsas the corresponding elements. An electrode core thin shaft centerportion 212Aa of an electrode core 21A in the present example includes athinnest portion 212Aa1 and a medium-thick portion 212Aa2. The thinnestportion 212Aa1 has a diameter Da and is positioned toward the couplingportion that couples to the spherical section 211. The medium-thickportion 212Aa2 has a diameter Db and is positioned toward the couplingportion that couples to an electrode core thick shaft center portion212Ab. The diameter Db is larger than the diameter Da and smaller thanthe diameter D2 of the electrode core thick shaft center portion 212Ab.It should be noted that the electrode core thick shaft center portion212Ab and an electrode core trailing end portion 212Ac of the presentembodiment have the same diameter as the electrode core thick shaftcenter portion 212 b and electrode core trailing end portion 212 c ofthe electrode core of the previously described embodiment, respectively,except that they have different axial lengths as compared with theircounterparts in the previously described embodiment.

In a case where the medium-thick portion 212Aa2 is configured to existin the space covered by the peripheral electrode 60, the diameter of themedium-thick portion 212Aa2 may be made equal to or greater than thediameter Do of the spherical section 211. Even in the case of thetapered electrode core thin shaft center portion 212 a of the core body20 in the previous embodiment, a portion of the electrode core thinshaft center portion 212 a that is positioned toward the electrode corethick shaft center portion 212 b may have a diameter equal to or greaterthan the diameter Do of the spherical section 211 when the electrodecore thick shaft center portion 212 b is configured to exist in thespace covered by the peripheral electrode 60.

FIG. 7B depicts a core body 20B having another example alternativeconfiguration. In the present example, too, elements identical to thoseof the core body 20 according to the previous embodiment are designatedby the same reference numerals as the corresponding elements. Anelectrode core thin shaft center portion 212Ba of an electrode core 21Bin the present example is such that the entire portion between thecoupling portion that couples to the spherical section 211 and anelectrode core thick shaft center portion 212Bb has the diameter Da,which is smaller than the diameter Do of the spherical section 211. Inthe other respects, the present example is similar to the previousembodiment.

It should be noted that, in the above example of the core body, theelectrode core thick shaft center portion and the electrode coretrailing end portion, which are included in the electrode core and notcovered with the resin, differ in thickness. Alternatively, however, theelectrode core thick shaft center portion and the electrode coretrailing end portion may be equal in thickness.

Further, in the previous embodiment, the electrode core thick shaftcenter portion is flush with and equal in diameter to a portion of theresin 22 that covers the electrode core thin shaft center portion.However, when the coupling portion between the electrode core thin shaftcenter portion and the electrode core thick shaft center portion ispositioned closer to the trailing end than the cylindrical section 121and is not positioned to oppose a wall surface 212 a of the cylindricalsection 121, the electrode core thick shaft center portion may differ indiameter from the resin 22 covering the electrode core thin shaft centerportion.

Alternative Embodiment and Modifications

In the electronic pen according to the previous embodiments, theperipheral electrode 60 is configured to be formed of a conductive coilspring. However, the peripheral electrode 60 is not limited to such aconfiguration. Alternatively, the peripheral electrode 60 may be formedof any cylindrically-shaped conductive material.

Further, the peripheral electrode 60 in the previous embodiments isformed of a single part. Alternatively, however, the peripheralelectrode 60 may be formed of a plurality of conductive membersseparated from each other in the circumferential direction.

Furthermore, in the previous embodiments, the pressure-sensitive partsof the pen pressure detection section are configured to form a variablecapacitor by sandwiching the dielectric between a terminal member and aconductive member. Alternatively, however, the pressure-sensitive partsmay be configured by using a semiconductor element that is configured asa variable capacitor formed of micro-electro-mechanical systems (MEMS)whose capacitance varies according to a pen pressure as disclosed, forexample, in Japanese Patent Laid-open No. 2013-161307.

Moreover, in the previous embodiments, a conductive coil spring is usedto electrically connect the electrode core of the core body to thecircuit on the printed circuit board. However, the electrical connectionto the circuit on the printed circuit board is not limited to such aconnection. An alternative configuration may be formed by electricallyconnecting the circuit on the printed circuit board to the core bodyholder to which the electrode core trailing end portion of the core bodyis fitted, or by electrically connecting the circuit on the printedcircuit board to the electrode core trailing end portion of the corebody.

Additionally, the previous embodiments have been described on theassumption that the core body has a circular cross-section.Alternatively, however, the core body may have a polygonal cross-sectioninstead of the circular cross-section.

In addition, the electrode core of the core body in the previousembodiments is formed of metal. However, the electrode core of the corebody need not always be formed of metal, and may alternatively be formedof a hard non-metallic material.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations arepossible depending on design requirements and other factors insofar asthey are within the scope of the appended claims or the equivalentsthereof

What is claimed is:
 1. A capacitive electronic pen. comprising: ahousing that is cylindrical in shape; a core body that has a distal endand a trailing end, the distal end protruding from one opening in anaxial direction of the housing, the trailing end being at an oppositeend from the distal end in the axial direction, and the core body beingdetachably fitted to a core body holder disposed in a hollow space ofthe housing; and a peripheral electrode that is positioned near the oneopening of the housing and formed of a conductor disposed so as tosurround at least a portion of the core body excluding the distal end,wherein the core body includes an electrode core formed of a conductorhaving a spherical section and a shaft center section, the shaft centersection being coupled to the spherical section, the spherical section ofthe electrode core is not surrounded by the peripheral electrode and isdisposed on the distal end protruding from one opening in the axialdirection of the housing, the shaft center section of the electrode corehas multiple portions that vary in thickness in the axial direction, theportions including a thin portion and a thick portion, the thin portionincluding a coupling portion that couples to the spherical section andthat is thinner than a diameter of the spherical section, and the thickportion being disposed toward the trailing end of the core body andbeing thicker than the coupling portion, and when the core body isfitted to the core body holder, at least a portion of the thin portionthat is not surrounded by the peripheral electrode is thinner than thediameter of the spherical section.
 2. The capacitive electronic penaccording to claim 1, wherein resin covers the spherical section of theelectrode core and at least a portion of the shaft center section thatis thinner than the diameter of the spherical section.
 3. The capacitiveelectronic pen according to claim 1, wherein the spherical section ofthe electrode core is disposed on the distal end that protrudes from theone opening of the housing and has a portion thicker than the shaftcenter section.
 4. The capacitive electronic pen according to claim 1,wherein a portion of the shaft center section that is thinner than thediameter of the spherical section is tapered in shape so as to graduallyincrease in thickness from the distal end toward the trailing end. 5.The capacitive electronic pen according to claim 1, wherein a portion ofthe shaft center section that is thinner than the diameter of thespherical section has a fixed thickness.
 6. The capacitive electronicpen according to claim 1, wherein a portion of the electrode core thatis positioned toward the trailing end is exposed without being coveredwith resin and is electrically connected to a signal output end of asignal generation circuit disposed in the housing.
 7. The capacitiveelectronic pen according to claim 1, wherein a portion of the electrodecore that is positioned toward the trailing end is exposed without beingcovered with resin and is fitted to the core body holder formed of aconductor, and the core body holder is electrically connected to asignal output end of a signal generation circuit disposed in thehousing.
 8. The capacitive electronic pen according to claim 1, whereinresin covers the spherical section of the electrode core and at least aportion of the shaft center section that is thinner than the diameter ofthe spherical section, and an inner wall surface is formed on the oneopening of the housing, the inner wall surface facing a circumferentialside surface of the resin covering the portion of the shaft centersection that is thinner than the diameter of the spherical section. 9.The capacitive electronic pen according to claim 8, wherein the corebody is axially displaceable in the hollow space of the housingaccording to a pressure applied to the distal end, and the inner wallsurface and the circumferential side surface of the resin covering theportion of the shaft center section that is thinner than the diameter ofthe spherical section are formed along the axial direction.
 10. Thecapacitive electronic pen according to claim 8, wherein a portion of theelectrode core that is positioned toward the training end is exposedwithout being covered with resin and has a circumferential side surfacethat is flush with the circumferential side surface of the resincovering the portion of the shaft center section that is thinner thanthe diameter of the spherical section, and the inner wall surface of theopening in the housing faces the circumferential side surface of theresin including a portion of the resin that couples with the exposedportion of the electrode core.
 11. The capacitive electronic penaccording to claim 1, wherein resin covers the spherical section of theelectrode core and at least a portion of the shaft center section thatis thinner than the diameter of the spherical section, and a portion ofresin that covers the spherical section is thicker than a portion ofresin that covers the portion of the shaft center section that isthinner than the diameter of the spherical section, and an inner wallsurface is formed in the one opening of the housing to face acircumferential side surface of the portion of resin that covers thespherical section.
 12. The capacitive electronic pen according to claim11, wherein the core body is axially displaceable in the hollow space ofthe housing according to a pressure applied to the distal end, and theinner wall surface and the circumferential side surface of the portionof resin that covers the spherical section are formed along the axialdirection.
 13. The capacitive electronic pen according to claim 1, a penpressure detector is disposed in the housing and positioned proximal tothe core body holder toward the trailing end, and the core body holderacts as a transmission member for transmitting, to the pen pressuredetector, the pressure applied to the distal end of the core body. 14.The capacitive electronic pen according to claim 1, wherein thespherical section and the shaft center section of the electrode core areformed of metal.